Electrical conversion system



p 1965 D. A. HAASE 3,209,232

ELECTRICAL CONVERSION SYSTEM Filed July 11, 1962 2 Sheets-Sheet 1 A 3 INVENTOR.

DON/4Z0 A. HAASE A T TOEWEV Sept. 28, 1965 D. A. HAASE 3 ELEC R L CONVERSION SYSTEM Filed July 11, 1962 2 Sheets-Sheet 2 United States Patent 3,209,232 ELECTRICAL CONVERSION SYSTEM Donald A. Haase, Rochester, N.Y., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed July 11, 1962, Ser. No. 209,120 3 Claims. ((31.32'1-50) This invention pertains to electric transmitters for speedometer drives, and particularly to an improved switch-type transmitter for converting direct current to three phase alternatingcurrent.

In my copending application Serial No. 183,067, filed March 28, 1962, a switch-type inverter is disclosed embodying a rotatable cam for sequentially actuating three movable contact blades into and out of engagement with three stationary contacts of one polarity and a centrally arranged contact ring of opposite polarity. The present invention is directed primarily to an improved and simplified construction of a switch-type transmitter. According- 1y, among-my objects are the provision of a switch-type transmitter having unitary bracket means for supporting each group of stationary contacts; the further provision of a switch-type transmitter wherein the movable contact blades are directly attached to the output terminals and have integral cam follower means; and the still further provision of a transmitter having a grooved rotatable cam for sequentially actuating the movable contact blades into and out of engagement with their respective set of stationarycontacts of opposite polarity.

The aforementioned and other objects are accomplished in the present invention by utilizing .a ring as a mounting bracket for the group of contacts of one polarity and a substantially triangular member as the bracket for the group of contacts of opposite polarity. Specifically, the two mounting brackets are coaxially arranged and supported by a cover of insulating material so that each contact of the inner bracket is aligned with a contact of the outer bracket to form a contact set. The triangular bracket with its input terminal, and three output terminals are located by molding the insulating material of the cover thereabout, while the ring bracket is aligned by dowels on the cover and held in assembled relation therewith when the cover is attached to the housing. The movable contact blades are secured to the output terminals and have oppositely facing contacts disposed between each set of stationary contacts. The integral cam followers of the movable contacts are seated in a cam groove of a cam plate such that upon rotation thereof the movable contacts will be sequentially moved into and out of engagement with the stationary contacts of their respective set.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIGURE 1 is a fragmentary view, partly in section and partly in elevation, of the improved transmitter assembly with connections thereto.

FIGURE 2 is an enlarged sectional view of the transmitter assembly taken along line 2-2 of FIGURE 3.

FIGURES 3 and 4 are sectional views taken along lines 33 and 4-4, respectively,

With reference to FIGURE 1, the improved transmitter includes a die cast metal housing having external thread segments 12 for receiving an insulative coupling 14. The insulative coupling 14 is used to securely connect a flanged socket member 1 6 to the transmitter housing 10, the socket member 16 having a cable 18 extending therefrom. As seen in FIGURE 2, the housing 10 is formed with a cup-shaped recess 20 which is closed by a cover 22 of insulating material. The cover 22 is secured to the housing 10 by a plurality of circumferentially spaced stakes 24.

Referring to FIGURE 3, an outer metallic mounting bracket 26, in the form of a ring, is located relative to the cover 22 by three axially extendingdowels 28. The mounting bracket v26 is formed with three inwardly extending tabs 30 spaced 120 apart, the tabs 30 having axially .oitset portions 32. A stationary contact 34 is connected by brazing to each tab portion 32, the contacts 34 constituting the outer group of contacts which are connected to one terminal ofa direct current source. More particularly, as seen in FIGURE 2, when the .cover 22 is assembled with the housing 10 the ring bracket 26 is clamped between the cover and the housing so as to be electrically-connected to the housing '10.

The cover 22 is molded around three output terminals 36 which project from both sides of the cover, and ,a centrally arranged input terminal 38 which is staked at 40 to an inner metallic mounting bracket 42 of substantially triangular configuration. The inner mounting bracket 42 has three axially extending tabs 44 projecting into the cup-shaped recess 20 of the housing 10, and a stationary contact 46 is connected to each tab 44 by brazing. The contacts 46 constitute the inner group of stationary contacts which are electrically connected to the other terminal of the direct current source through the input terminal 38, the socket 1.6 and a wire in the cable 18.

As clearly seen in FIGURES 3 and 4, the stationary contacts 46 of the inner group are likewise spaced substantially 120 apart, and each is aligned with contact 34 of the outer group to form a contact set. In each contact set the contact 34 is of one polarity while the contact 46 is of opposite polarity.

The inwardly extending portions of the output terminals 36 have spring reeds, or blades, 48 attached thereto by rivets 50. Each contact blade 48 has an outer contact 52 and an inner contact 54 connected thereto by brazing, the contacts 52 and 54 being arranged back to back and disposed between a set of .stationary contacts. The outer contacts 52 of the blades 48 are adapted to engage stationary contacts 34 while the inner contacts 54 are adapted to engage stationary contacts 46. The output terminals 36 are likewise spaced 120 apart as shown in FIGURES 3 and 4.

Each spring reed, or blade, 48 is formed with an integral, axially extending cam follower portion 56. The cam follower portions 56 are formed by rolling over the end of each spring reed 48. The cam follower portions 56 are seated in a cam groove 58 of a disc, or cam plate, 60. The disc 60 has an integralhub portion 62 journalled in the housing 10 by a sleeve bearing 64 and restrained against axial movement by a retaining ring 66. The disc 60 is composed of insulating material and bears against a washer 68 confined between the disc and the housing 10. A lip-type oil seal 70 is disposed between the washer 68 and the bearing 64. The hub 62 of the disc 60 is suitably connected to an input drive shaft 72 of polygonal crosssection.

Upon rotation of the disc 60, the contact carrying blades 48 will be sequentially deflected by reason of the cam followers 56 engaging the cam groove 58. Accordingly, the contact 52 of each blade 48 will be moved into and out of engagement with stationary contact 34, and the contact 54 will be moved into and out of engagement with the stationary contact 46. The requisite contact pressure is obtained by bending, or deflecting the blades 48. Since the cam groove 58 comprises two diametrically opposed symmetrical halves, during each mechanical revolution of the disc 60 the respective movable contacts will be actuated throughout two complete cycles. In this manner the alternating current electrical signal generated will have an electrical frequency twice that of the mechanical frequency of the disc 60.

The transmitter converts direct curent battery voltage to a three phase, alternating current staircase signal by sequentially connecting the three output terminals 36 to positive, negative, or zero potential. The signal generated can be used to energize the coils of a synchronous receiver motor and thus indicate the speed of rotation of the shaft 72.

While the embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A transmitter including, a plurality of circumferentially spaced movable contact blades, first and second groups of stationary contacts of opposite direct current polarity, each group comprising a plurality of circumferentially spaced contacts, the contacts of one group being spaced from the contacts of the other group to form a plurality of stationary contact sets equal in number to the number of movable contact blades, and rotatable cam means engageable with said movable contact blades for sequentially deflecting said blades into and out of engagegment with the stationary contacts of their respective contact set to produce a polyphase alternating current signal having a frequency proportional to the rotative speed of said cam means.

2. A transmitter including, a first group of stationary contacts, a second group of stationary contacts aligned with and spaced from said first group, each group including a like number of circumferentially spaced contacts With aligned contacts of said groups forming circumferentially spaced contact sets, each set having a pair of stationary contacts of opposite direct current polarity, a movable contact blade disposed between the stationary contacts of each set, and rotatable cam means engageable with said movable blades for sequentially deflecting said blades into and out of engagement with the stationary contacts of their respective set to produce a polyphase alternating current signal having a frequency proportional to the rotative speed of said cam means.

3. A transmitter comprising, a housing having a cupshaped recess, a cover of insulating material for closing the open end of said cup-shaped recess, a ring-type mounting bracket clamped between said cover and said housing and carrying a first group of stationary contacts, a mounting bracket supported centrally of the cover and carrying a second group of stationary contacts located inwardly of said first group and aligned therewith, each group comprising alike number of circumferentially spaced contacts with the contacts of said first and second groups being of opposite direct current polarity, aligned contacts of said first and second groups being arranged in circumferentially spaced sets, a plurality of output terminals in said cover, a movable contact blade carried by each output terminal and arranged between each set of stationary contacts, and rotatable cam means journalled in said housing for sequentially deflecting said movable contact blades into and out of engagement with the stationary contacts of their respective set to produce a polyphase alternating current signal having a frequency proportional to the rotative speed of said cam means.

4. A transmitter comprising, a metallic housing having a cup-shaped recess, a cover of insulating material for closing the open end of said cup-shaped recess, first unitary metal bracket means clamped between said cover and said housing and carrying a first group of stationary contacts, second unitary metal bracket means supported centrally of the cover and carrying a second group of stationary contacts located inwardly of said first group and aligned therewith, each group comprising a like number of circumferentially spaced contacts with the contacts of said first and second groups being of opposite direct current polarity, aligned contacts of said first and second groups being arranged in circumferentially spaced sets, a plurality of output terminals extending through said cover, a movable contact blade attached to each output terminal and arranged between each set of stationary contacts, and rotatable cam means journalled in said housing for sequentially deflecting said movable contact blades into and out of engagement with the stationary contacts of their respective set to produce a polyphase alternating current signal having a frequency proportional to the rotative speed of said cam means.

5. The transmitter set forth in claim 4 wherein said first unitary bracket means comprises a ring having a plurality of inwardly extending tabs with axially oflset portions, said first group of stationary contacts being attached to the axially offset portions of said tabs.

6. The transmitter set forth in claim 4 wherein said second unitary bracket means comprises a substantially triangular member having a plurality of axially extending tabs, and wherein the stationary contacts of the second group are attached to said tabs.

7. The transmitter set forth in claim 4 wherein said movable contact blades comprise spring reeds having contacts attached thereto in back-to-back relationship.

8. The transmitter set forth in claim 7 wherein said rotatable cam means comprises a disc having a cam groove in the face thereof, and wherein said spring reeds have axially extending rolled ends disposed in said cam groove and constituting integral cam followers for actuating said contact blades.

References Cited by the Examiner UNITED STATES PATENTS 2,523,993 9/50 McCandless 318-25 2,651,750 9/53 Koppelman et al 32148 FOREIGN PATENTS 566,471 1/45 Great Britain. 960,698 3/57 Germany.

LLOYD MCCOLLUM, Primary Examiner, 

4. A TRANSMITTER COMPRISING, A METALLIC HOUSING HAVING A CUP-SHAPED RECESS, A COVER OF INSULATING MATERIAL FOR CLOSING THE OPEN END OD SAID CUP-SHAPED RECESS, FIRST UNITARY METAL BRACKET MEANS CLAMPED BETWEEN SAID COVER AND SAID HOUSING AND CARRYING A FIRST GROUP OF STATIONARY CONTACTS, SECOND UNITARY METAL BRACKET MEANS SUPPORTED CENTRALLY OF THE COVER AND CARRYING A SECOND GROUP OF STATIONARY CONTACTS LOCATED INWARDLY OF SAID FIRST GROUP AND ALIGNED THEREWITH, EACH GROUP COMPRISING A LIKE NUMBER OF CIRCUMFERENTIALLY SPACED CONTACTS WITH THE CONTACTS OF SAID FIRST AND SECOND GROUPS BEING OF OPPOSITE DIRECT CURRENT POLARITY, ALIGNED CONTACTS OF SAID FIRST AND SECOND GROUPS BEING ARRANGED IN CIRCUMFERENTIALLY SPACED SETS, A PLURALITY OF OUTPUT TERMINALS EXTENDING THROUGH SAID COVER, A MOVABLE CONTACT BLADE ATTACHED TO EACH OUTPUT TERMINAL AND ARRANGED BETWEEN EACH SET OF STATIONARY CONTACTS, AND ROTATABLE CAM MEANS JOURNALLED IN SAID HOUSING FOR SEQUENTIALLY DEFLECTING SAID MOVABLE CONTACT BLADES INTO AND OUT OF ENGAGEMENT WITH THE STATIONARY CONTACTS OF THEIR RESPECTIVE SET TO PRODUCE A POLYPHASE ALTERNATING CURRENT SIGNAL HAVING A FREQUENCY PROPORTIONAL TO THE ROTATIVE SPEED OF SAID CAM MEANS. 